The following abbreviations are used throughout this document:
CEP Customer Edge Port
CNP Customer Network Port
C-VLAN Customer VLAN
C-VID Customer VLAN identifier
IEEE Institute of Electrical and Electronics Engineers
LER Label Edge Router
LSP Label Switched Path
LSR Label Switching Router
MAC address Media Access Control address
MCP MPLS Customer Port
MNP MPLS Network Port
MPLS Multiple Protocol Label Switching
MPLS-TP MPLS Transport Profile
PB Provider Bridge
PB-network Provider Bridged network
PEB Provider Edge Bridge
PEP Provider Edge Port
PNP Provider Network Port
S-VLAN Service VLAN
S-VID Service VLAN identifier
VLAN Virtual Local Area Network
Ethernet has over the years become a common Local Area Network (LAN) technology. This achievement stems from the some characteristics of the technology, such as simple handling, the relatively low costs involved, convenient manageability and backward compatibility.
Also, the MEF (Metro Ethernet Forum) Ethernet services has contributed to the development of Ethernet technologies beyond the LAN environment resulting in functionalities for the support of advanced OAM (Operations, Administration and Maintenance), scalability and manageability. The main bulk of this effort is associated with various projects related to the interworking subgroup in IEEE 802.1. For example, the IEEE 802.1ad (provider bridges, or PB), the IEEE 802.1ah (provider backbone bridges, or PBB), the IEEE 802.1Qay (provider backbone bridges—traffic engineering, or PBB-TE), and the IEEE 802.1ag (connectivity fault management, or CFM) standards have addressed the issues of creating provider services using Ethernet infrastructure, scaling Ethernet networks, of supporting traffic engineered services and managing faults of Ethernet services.
Provider bridges, in particular, which is the first bridging technology standardized by IEEE for provider applications, enabled Ethernet and Ethernet bridging to rapidly become the technologies of choice for provider access and aggregation networks. It solves two problems presented by the application of enterprise IEEE 802.1Q bridges to provider networks. The first problem is separating the customer virtual LAN (VLAN) space from the provider VLAN space, and the second problem is allowing the provider the ability to multiplex many customer VLANs on a single provider VLAN. To address these problems a provider bridge supports the creation of service VLANs (S-VLANs) within an independent VLAN space that is controlled by the provider and used to carry customer VLANs (C-VLANs).
Multiprotocol Label Switching (MPLS), an architecture for fast packet switching and routing and provides the designation, routing, forwarding and switching of traffic flows through a network. More specifically, MPLS has mechanisms to manage traffic flows of various granularities and provides a way to map IP addresses to simple, fixed-length labels used by different packet-forwarding and packet-switching technologies. In MPLS, data transmission occurs on Label-Switched Paths (LSPs). The entry and exit points of an MPLS network are called Label Edge Routers (LERs). The entry LER pushes an MPLS label onto an incoming packet based on its destination and forwards the packet to the next Label Switch Router (LSR) on the LSP to the destination. The LSR will strip the label from the packet, look up the label to determine the next label to be applied to the packet and the next hop for the path, and forward the packet onward to the next hop. In this way, the packet is forwarded hop-by-hop across the LSP through the MPLS network.
MPLS Transport Profile (MPLS-TP) is proposed to enhance MPLS's capabilities and mechanisms to meet the requirements of transport network operations.
Today it is expected that some network operators want to migrate from an Ethernet network (or more specifically a PB-network) to an MPLS/MPLS-TP network when it becomes available. Migration from PB based services to MPLS/MPLS-TP based services may take a long time since Ethernet based networks and MPLS based networks use different technologies for routing and forwarding data in the respective network, and since the operators must negotiate with each single customer to keep any service disruption to a minimal level. Ideally, the Ethernet based services should be kept as before while at the same time MPLS based services can be offered to the customer.